REDUCTIVE CARBONYLATION OF NITROBENZENE TO N,N-DIETHYL-N'-PHENYLUREA

Reductive carbonylation of nitrobenzene with carbon monoxide and dieth ylamine at 363-443 K and initial CO pressures 6-17 MPa in the presence of a catalyst consisting of sulfur or a sulfur compound and a vanadiu m(Ti) compound in a basic medium yields N,N-diethyl-N'-phenylurea as t he main product. Formation of the side products (aniline, N,N'-dipheny lurea, and N-phenylformamide) is affected significantly by water admix tures. The efficiency of sulfur components increases in the order: S : CS2 : H2S : COS = 1 : 1.2 : 5.7 : 8. The presence of the vanadium(V) compound, although not prerequisite, has promoting effect. The selecti vity and reaction rate of the carbonylation increases with increasing CO pressure. Water affects negatively above all the selectivity of the reaction (at 0.24 wt.% water in diethylamine, maximum selectivity exc eeds 80%, at. 1.6 wt.% water it is only ca 60%). The effect of reactio n conditions and the course of side reactions is discussed.